Web APIs allow users to interact with content they create and incorporate multiple functions on a single site. An API is a defined set of HTTP request and response messages, typically in JSON or XML format, that enables access to functions and data on a website or application. Many popular sites like Google Maps, Mapquest and Twitter expose APIs to enable third-party access and integration.

1. Web APIApplicationProgrammingInterface

2. First, let’s define Web 2.0Incorporate content in which the user interacts with content they've created

3. API usually incorporates multiple functions on one siteWhat is API?... a defined set of HTTP request messages along with a definition of the structure of response messages, typically expressed in JSON or XML.(say that five times, fast)

4. Google Maps, Mapquest, Twitter...There are COUNTLESS API’s